Whether a proposed Temecula-area rock quarry gets built hinges on a vote scheduled for this morning by the Riverside County Board of Supervisors.

The board will meet at 8:30 a.m. in Riverside to conclude its hearings on the Liberty Quarry, which raised questions about how to balance economic development, the environment and quality of life.

Quarry developer Granite Construction appealed the county Planning Commission’s rejection of the quarry, sought for a 414-acre site between Temecula’s southern border and the San Diego County line. Commissioners held six hearings and listened to nearly 52 hours of public comments before voting 4-1 in August to reject the quarry.

For 75 years, Granite wants to use explosive blasts to extract up to 270 million tons of aggregate, a building material consisting of tiny rocks.

Asphalt and concrete would be made on-site at the quarry off Interstate 15. It would be a mile long and up to 1,020 feet deep. By comparison, the Empire State Building is 1,250 feet tall.

The project was first proposed in 2005 by Granite, a one-time Fortune 500 corporation based in Watsonville with revenues of $1.8 billion in 2010. It is active in 18 states and makes most of its money by building roads and other infrastructure.

Divisive issue

Granite and a coalition of labor unions and business groups contend the quarry will provide nearly 300 jobs – about 100 averaging $100,000 a year in salaries and benefits – as well as $300 million in sales tax revenue and $41 million in property tax fees. It would solve a looming aggregate shortage while respecting the environment and improving air quality by taking diesel trucks off the road, supporters say.

Five Inland city councils, including Eastvale, Moreno Valley, Banning and Beaumont, have endorsed the quarry.

On the other side are Temecula-area residents, environmentalists, a coalition of doctors and others who accuse Granite of waging a misinformation campaign. They say the quarry would worsen air pollution through increased truck traffic and the spewing of microscopic silica dust through daily wind currents into nearby communities.

Opponents say the quarry won’t add jobs, but take them from other quarries while ruining the local tourism industry and research at a neighboring ecological reserve. Groundwater would dry up, a coastal wildlife linkage would be severed and a sacred Pechanga Band of Luiseño Indians site would be destroyed if the quarry is built, according to critics.

The tribe and Temecula City Council oppose the quarry. Pechanga pushed legislation in Sacramento that would kill the quarry. That bill remains in limbo.